The Mechanism Study Of The Effects Of Root Restriction On The Fruit Quality Of Grape Berry

In present study,the effects of root restriction（RR）on the main primary and secondary metabolites,and related genes in the grape berry（Vitis vinifera xVitis labrusca）at different developmental stages were studied at the transcriptomic and metabolomic level,using ’Summer Black’ grape berry as materials.The main results were as follows:1.A total of 29,971 genes were generated by RNA-Seq in grape berries over the all course of developmental stages in the root restriction and control treatments,among which a total of 1,606 significantly differential expression genes were found.The qRT-PCR analysis was performed to confirm the accuracy and reproducibility of RNA-Seq results.Linear regression analysis showed an overall correlation coefficient of 0.85,indicating a consistency of qRT-PCR results and RNA-Seq results,suggesting the reliability of the RNA-Seq data.2.The primary metabolites such as ascorbic acid（AsA）,sugars,organic acids,amino acids,starch,pectin and cellulose were qualitatively and quantitatively analyzed,along with their metabolic pathways.RR treatment significantly increases the contents of AsA,and the gene VIT₀8s0040g03150 codes for L-ascorbic acid peroxidase related to AsA recycling pathways may be the main regulator for AsA contents;Sucrose synthase（SS）and sucrose phosphate synthase（SPS）were inferred to play critical roles in the RR-induced accumulation of starch,sucrose,glucose and fructose,and promoted the malic acid and tartaric acid accumulation in the young fruits,promoted the proline accumulation and phenylalanine degradation in the ripe fruit.In addition,fruits from RR treatment tend to have lower pectin and cellulose content.3.Carotenoid compositions were determined by high performance liquid chromatography（HPLC）.The carotenoid biosynthesis pathways were also analyzed.The contents of most of the carotenoids were significantly increased by RR treatment at the early developmental stages,and the phytoene synthase（PSY）and beta-carotene 3-hydroxylase（crtZ）were inferred to play the major roles.A total of seven phenolic acids compounds,three stilbenes compounds,nine flavonols compounds,ten anthocyanins compounds and twenty-four procyanidins compounds were determined by ultra performance liquid chromatography-high resolution mass spectrometer（UPLC-HRMS）.The phenylalanine metabolic pathways were also analyzed.RR treatment significantly promotes the phenolic acids,resveratrol,flavonols and anthocyanins biosynthesis.Meanwhile,RR treatment significantly affected the procyanidins contents,which were increased at the early developmental stages then decreased at the late developmental stages.Phenylalanine ammonia-lyase（PAL）,trans-cinnamate 4-monooxygenase（CYP73A）,4-coumarate-CoA ligase（4CL）,shikimate O-hydroxycinnamoyltransferase（HCT）,chalcone synthase（CHS）,chalcone isomerase（CHI）,stilbene synthase（STS）,flavonoid 3’,5’-hydroxylase（CYP75A）,anthocyanidin 3-O-glucosyltransferase（BZ1）expression levels were inferred to play critical roles in these changes regulated by RR treatment.4.A total of 23 genes involving in phytohormones biosynthesis pathways were significantly changed by RR treatment in the whole developmental period.The RR treatment increased the abscisic acid,brassinosteroid and salicylic acid levels,while decreased the auxin,cytokinin,and gibberellin contents in the fruit,and finally,accelerated the grape ripening process.